50 



NATURE 



[Nov. 21, 1889 



deavouring to effect a compromise between purely ele- 

 mentary works on astronomy and advanced treatises, it 

 is worthy of some praise. With the many remarkable 

 developments of astronomical science during the last 

 quarter of a century, the bulk of the original volume has 

 been somewhat increased by additions, and it has now 

 been decided henceforth to publish the work in three 

 divisions, viz. — 



(i) The sun, planets, and comets. 



(2) Instruments and practical astronomy. 



(3) The starry heavens. 



The first division of the work is now before us, and 

 viewed as a handy book of reference it has many com- 

 mendable features ; but all that could be said in its 

 praise would be the reiteration of comments upon former 

 editions. 



The most important application of spectroscopy to 

 astronomy is too well known to need any enlarging upon. 

 It may be said to be almost entirely a creature of the last 

 quarter of a century, but by far the greater amount of 

 this spectroscopic work has been directed to the sun, 

 whilst many new and important discoveries have been 

 made in connection with it. In pre-spectroscopic times 

 a spot on the sun was only that, and nothing more ; and 

 a solar prominence was a stupendous flame, the observa- 

 tion of which was only possible at eclipses. Nothing 

 was known of their constitution ; and, in fact, all we now 

 know of the physical and chemical condition of the sun 

 has been gained by spectroscopists. However, it is not 

 necessary here to consider the enormous work that has 

 been done in this direction, but it is our duty most em- 

 phatically to protest against a compilation such as the one 

 before us — purporting to be a completely revised account 

 of astronomical labours and advances, and yet render- 

 ing terribly conspicuous by its absence everything that 

 relates to spectroscopy. It is like a book on loco- 

 motion leaving out all about railways because they 

 were not prominent when the first edition was pub- 

 lished. The pictorial representations of the corona, the 

 solar prominences, the surface of the sun and the spots 

 upon it, are well discussed in their respective sections, 

 but no room has been given to an examination of their 

 constitution by means of the spectroscope ; and indeed, 

 as far as this book is concerned, the whole work that has 

 been done in connection with solar physics might have 

 been left undone. 



But these remarks apply not only to the chapters re- 

 lating to the sun ; those on the planets and comets re- 

 spectively are in the same incomplete condition. Without 

 the spectroscope, the source of luminosity of a comet was 

 far beyond human ken, and its whole constitution was a 

 matter of considerable doubt ; with this instrument, how- 

 ever, much has been added to our knowledge — the comet's 

 light has been analyzed, and the whole sequence of 

 changes, as it goes from aphelion to perihelion and back 

 again, is now understood. Yet the spectroscope might 

 never have been turned to these bodies, or indeed utilized 

 in any way, if the utility and importance of the work 

 done were measured by the brief notice with which the 

 author has seen fit to dispose of it, and the following may 

 be said to be the reason for his grievous omissions : — 



" The study of the sun has during the last few years 

 taken a remarkable start, owing to the fact that, by the 



aid of the spectroscope, we have been enabled to obtairt 

 much new information about its physical constitution. 

 The subject being, however, a physical rather than an 

 astronomical one, and involving a great amount of optical 

 and chemical details, it cannot conveniently be discussed 

 at length in a purely astronomical treatise, though some- 

 thing will be said concerning it later on in the portion of 

 this work dedicated to spectroscopic matters." 



This explanation, however, only aggravates the fault. 

 The importance of the work that has been done is as- 

 sented to, but, instead of including that part of it relating 

 to the sun in a chapter on that body, instead of consider- 

 ing the spectroscopy of comets as inseparable from a 

 chapter devoted to their discussion, the author has rele- 

 gated the whole work to an unpublished section devoted to 

 astronomical instruments. Such an arrangement is un- 

 doubtedly wrong. A chapter on the sun must contain all 

 that is known about that body, if it strives to be at all com- 

 plete ; similarly, a chapter on comets cannot approach 

 completion unless their spectra are considered ; thus this 

 work cannot lead the general public to a just appreciation of 

 the many advancements that have been made. The most 

 elementary text-books rightly include the spectroscopic 

 labours and discoveries, whereas this so-called hand-book, 

 although aiming at being an historical account of the 

 work that has been directed to the sun, planets, and 

 comets respectively, leaves a vast array of facts out of 

 consideration altogether. 



There are a few minor faults, one of which is the 

 figure relating to Foucault's pendulum experiment for 

 determining the rotation of the earth. The author ap- 

 pears to have discarded the method of suspension 

 adopted by Foucault, and the pendulum is sketched as 

 if rigidly attached to a beam. The accompanying text 

 also leaves this most important experimental detail out 

 of consideration. 



But apart from these points, the work is worthy 

 of some commendation. An addition has been made to 

 the chapter on comets, viz. a method of determining the 

 elements of the orbit of a comet by a graphical process. 

 The catalogue of comets whose orbits have been com- 

 puted has also been brought up to date, and similar ad- 

 ditions have been made to the chapters on periodic and 

 remarkable comets. Doubtless the book will prove to be 

 what it has been heretofore — a handy reference to some 

 astronomical facts. 



ELECTRICAL UNDERTAKINGS. 



Proceedings of the ^National Electric Light Association 

 at its Ninth Co?ivention, 1889. Vol. VI. (Boston, 

 Mass., U.S. : Press oi Modern Light and Heat, 1889.) 



WE have before us, in this volume, an account of the 

 proceedings of the National Electric Light Asso- 

 ciation in the United States during the Convention held 

 at Chicago on certain days in February 1889. 



This body is one which, in the United States, has been 

 brought into existence by the growing necessities and 

 rapid expansion of the electric light and power industry. 

 Probably its nearest English analogue is the Iron and 

 Steel Institute. It is essentially a commercial associa- 

 tion, and its aims may be said to be comprised within 

 the limits of the exchange of practical information 



